The following is not an admission that anything discussed below is part of the prior art or part of the common general knowledge of a person skilled in the art.
A surface cleaning apparatus, more commonly known as a vacuum cleaner or vacuum, may be used to clean a variety of surfaces using at least suction. Various types of vacuum cleaners are known including, without limitation, upright vacuum cleaners, canister vacuum cleaners, stick vacuum cleaners, and central vacuum systems. A vacuum cleaner typically includes a surface cleaning head with a dirty air inlet. Some vacuum cleaners include some or all of the operating components (e.g., the suction motor and the air treatment system) at a location other than the surface cleaning head to enable the surface cleaning head to be lighter or smaller. An upright vacuum cleaner, for example, may include an upright section containing at least an air treatment system and mounted to a surface cleaning head. A canister vacuum cleaner may include a canister body containing at least an air treatment system and a suction source (e.g., a suction motor) that is connected to a surface cleaning head by a flexible hose and a handle. Another type of vacuum cleaner includes the suction motor and the air treatment system (e.g., one or more cyclones) positioned in the surface cleaning head.
A surface cleaning apparatus, such as any of the vacuum cleaners mentioned above, may also use one or more cleaning sheets or pads. Examples of surface cleaning heads using both suction and cleaning sheets or pads are disclosed in U.S. Design Pat. No. 681,899 and U.S. Patent Application Pub. No. 2014/0331445, which are commonly owned and incorporated herein by reference. While using these surface cleaning heads, the cleaning sheets or pads generally collect debris while sliding across a cleaning surface together with the suction conduit or nozzle. In the surface cleaning heads where the cleaning sheet or pad is fixed relative to the suction conduit or nozzle, however, the force exerted on the cleaning sheet or pad may not be appropriate to ensure that the cleaning sheet or pad collects debris from the surface to be cleaned. The problem of exerting an appropriate amount of force is further exacerbated when the surface to be cleaned is uneven. An uneven surface may cause the suction conduit or the cleaning sheet or pad to lose contact with the surface and thus reduce the cleaning effectiveness.